Storm Water Infiltration into Sanitary Sewer Lines

We are experiencing significant overflow of our sewage treatment plant during spring snow melt and during heavy rains. I have heard of slip lining sewer lines but not sure it is practical or cost effective for smaller systems (6" and 8" lines). Anyone out there with similar problems and how did you solve them? I would think there might be a spray on or foam product to coat and seal the inside of the pipes? Thanks for any suggestions.